1. Field of the Invention
The present invention relates to a juice extractor or a juicer and more particularly to an improvement in a juicer which is used mainly at home and at restaurants.
2. Prior Art
A juice extractor or a juicer is a device for extracting juice from foodstuffs such as vegetables, tubers, and fruits. Presently juicers come in basically two types: a centrifuge type juicer and a squeezing-type juicer.
A typical centrifuge type juicer includes an upright work container with a rotatable cutter at the bottom. This type of juicer is most suitable for extracting juice from fruits. When making juice from foodstuffs such as vegetables and tubers which contain a large amount of fiber and a low water content with such a juicer, the rate of juice extraction is not very high even when the blades are rotated at a considerably high speed. Thus, the problem involved in this type of juicer is that the residue still contains some liquid therein.
On the other hand, the squeezing-type juicer is most suitable for processing hard foodstuffs such as vegetables and fibers. These foodstuffs are compressed or sliced and then compressed so that juice is extracted from the foodstuffs. This type of juicer typically uses a pair of helical gears which are meshed with each other so that the foodstuff put between the gears are crushed and squeezed so that juice is extracted.
These juicers are disclosed in, for example, U.S. Pat. Nos. 4,4440,074, 5,156,872 and 5,381,730. In these types of juicers, the juice extraction ratio is several times higher than that of centrifugation-type juicers, and these types of juicers have the advantage of preventing residual heavy metals from flowing out together with the juice.
FIG. 11 shows one of the squeezing-type juicers invented by the inventor of the present patent application. A patent application for this juicer was filed in the U.S. Patent Office on Dec. 23, 1994, and a patent was issued on Sep. 26, 1995 under U.S. Pat. No. 5,452,650.
This juicer uses a pair of helical gears 1 and a pair of Archimedes' screws 2. The foodstuff squeezed by the helical gears 1 is transferred to the Archimedes' screws 2 so that juice and residues are guided by the Archimedes' screws 2. The juice is discharged from the juicer through the screen 3, and the residues are fed out through the residue outlet 5.
However, with any of the prior art juicers as listed and described above, a complete or a substantially complete extraction of juice from the foodstuff cannot be accomplished. In other words, the residues produced by the juice-extraction process still contain some amount of liquid therein. Thus, discarding such a residue is a waste of foodstuff that should be avoided.